It looks like there are no Android 4.4 images ready yet for this. In the download area of the Android X86 project you can find a couple of images and more, starting with Android 1.6 (Donut) and currently reaching up to Android 4.3 (Jelly Bean), and also other useful resources. Might be worth checking there again later, as I would expect they add 4.4 as soon as they have an image ready for that.
I'm not sure whether the Genymotion project (the "next generation" of AndroidVM) offers some image downloads as well, as checking would require one to sign-up first. Genymotion is another VM solution, which AFAIK works together with VirtualBox. It should be quite fast and stable, is based on Android x86, and available for MacOS, Linux, and Windows alike.
EDIT (2014-10-31): The download-area now holds the 4.4 images. A second place to check is the project's downloads at sourceforge, which currently also have the 4.4 images available.